A certain fluorine-containing silane compound is known to be able to provide excellent water-repellency, oil-repellency, antifouling property, or the like when it is applied to a surface treatment of a base material. A layer (hereinafter, referred to as a “surface-treating layer”) formed from a surface-treating agent comprising a fluorine-containing compound is applied to various base materials such as a glass, a plastic, a fiber and a building material as a so-called functional thin film.
As such fluorine-containing silane compound, a perfluoropolyether group containing silane compound which has a perfluoropolyether group in its molecular main chain and a hydrolyzable group bonding to a Si atom at its molecular terminal or terminal portion is known (see Patent Documents 1 and 2). When the surface-treating agent comprising the perfluoropolyether group containing silane compound is applied to a base material, a reaction of the hydrolyzable group bonding to a Si atom between the compound and the base material and between the compounds is occurred to form the surface-treating layer.